Chesapeake Bay Program - River Otter

<body> The northern river otter is a playful, quick and graceful animal that is spends most of its life in the rivers, marshy ponds and wooded riparian areas of the Chesapeake and its rivers. River otters belong to the Family Mustelidae, which includes 65 other species, including badgers, weasels, skunks and mink. Lutra canadensis is a gregarious, playful aquatic mustelid, and if undisturbed by humans may be active by day in groups, contrary to the solitary and nocturnal habits of its some of its relatives. Most mustelids are small carnivorous mammals with short legs, soft, thick pelts and paired anal scent glands. Unlike its cousin the skunk, which can scatter its powerful scent as far as 15 feet, the river otter’s glands produce secretions used for sexual and social signals rather than defense. The river otter is the largest of the mustelids and adapts well to its environment. Fossil remains of this species date to the Pleistocene period. In water the energetic otter has few natural predators, and except for young otters (which may be taken by foxes or raptors), most otter mortality, when not due to natural causes, is caused by human activity. Diving into the water .avi (1.3 MB) Otters at play .avi (2.5 MB) About the otter exhibit .avi (12 MB) Photos and video taken at the Calvert Marine Museum In the Midwest, otter populations were nearly eradicated by the end of the 18th century. In some parts of the United States, otters are caught accidentally in beaver traps. Water and air pollution, including mercury fallout, have harmed otter populations. Some may be developing tolerance to toxic substances, as their populations are slowly increasing. In North America the river otter’s range extends to most major waterways, in the north from Alaska and most of Canada, along the East Coast from Newfoundland to Florida, and in the west from northern California to northern Utah. Otter populations have increased slowly on Maryland’s eastern shore. Some have been captured from the eastern shore and released in other parts of the state where they have become scarce The northern river otter has a wide, flattened head and long, sleek, muscular body and tail. Adults of both sexes may grow to a total length of 52 inches, with about a 20-inch tail. Mature animals may weigh 30 pounds. The river otter has dark brown fur, with a paler underbelly and grayish throat. The otter’s eyes are small and close-set near the top of the animal’s head, which allow it to see even when the rest of its body is submerged in water. Its ears, like those of most mustelids, are small and rounded. Its prominent, white-tinged facial whiskers allow it to sense prey movements in the water. The otter’s long tail is thick at the base of the spine and tapers to a point, and it has webbed feet. Its subcutaneous layer of fat and oily coat allow it to tolerate icy water temperatures. The otter also has an acute sense of smell. River otters vocalize, by whistling, which is to communicate over distances, and shrill chatter call, during mating season. They feed on fish, crayfish, crabs, frogs and small mammals, including beaver kits. River otters are active and playful by day if not disturbed by humans and sometimes may be seen playing in small family groups. They are well-adapted to aquatic life, with streamlined body, rudderlike tail, ears and nostrils have valves to shut out water. River otters can swim rapidly underwater and on the surface, moving like flexible torpedo, either forward or backward with astonishing grace and power. They can remain submerged for several minutes, swim up to a quarter mile underwater, and dive to 55 feet. River otters are comfortable on land as well. They can run up to 15-l8 m.p.h. They often run and slide -- gliding as much as 25 feet on ice and ending with a tumble into a snowdrift or splash into the water. Mud, ice or snow slides are the best known evidence of otters. Several other signs of river otters are: Rolling places – Otters often leave areas of flattened vegetation, with musk or droppings. Haul-outs – Otters create trails coming out of the water that contain parts of shellfish and droppings. Scat – Otter excrement which is irregular is sometimes seen in short, rounded segments or flattened masses, containing fish bones, scales or crayfish parts. When scat is fresh, it appears greenish and slimy. Trails – Otter trials are about 8 inches wide and may show only the otters heel pad and claws. An otter track shows its toes fanned widely but doesn’t show its webbing. </body>